I am using quite a similar method for 4, 5 screens basically to do same thing on List of different objects. Now I extracted that method to reuse it and make it generic. Now while making a list generic I face the issue with attributes. It’s attributes are no longer accessible when made generic. How to ov…
Tag: generics
How to implement a generic interface that extends another generic interface in Java?
I am new to Java and working on implementing generic interfaces and that’s where I’d love some help. I want to implement a generic interface in Java that extends another interface. This is how the current interface structure looks like – I want to implement the ItemsProviderInterface interfa…
Is it possible to cast an instance of List<ArrayList> to List<List> in O(1) time in Java?
I have an instance of List<ArrayList<Integer>>, how can I change it to type List<List<Integer>> ? My solution is: However, this method takes time O(n), with n the length of list1. Question1: Is there better method? The following naive method is compile error: Question2: why is above me…
Why java lets me add a Box(Raw type) to a List<Box>
This code works, and I dont understand how the list is able to add a raw type box, I thought type erasure will set the type to their indicated bounds. note: Paper class doesn’t extends Bakery class. EDIT: Is my understanding correct? the compiler typecasts the raw box type so that it can be added to the…
How to extends from generic type and override method parameter type with subclass
I have a problem with generic class hierarchy and method override. I tried to do something like below: and the subclass looks like: However, subclass does not compile and I have no clue how to declare method in Configuration class so I can override it in subclass with subclass type as parameter. I want to avo…
Need Help converting JavaObject To Json in Generic Pattern
I wrote a Generic method which works fine converting any Json object to Generic Object. But has an issue while converting the Generic Object type to JSON format with the below code format. Would someone help me or guide me with related code.. I am not sure how to retain an Object from Generic class type as th…
Why can’t I add a type parameter to an overriding method?
I need to implement a method from a class Foo, in my subclass Bar: As you can see, my method would benefit from a type parameter: (I could also use raw types because I know it’ll work, but everything I’ve read says you really shouldn’t do that) Unfortunately, this is illegal – my metho…
Is there a way to see what my code looks like after type erasure?
I would like to know what tool can be used to view code after type erasure. For example, I’d like to see what the following code looks like after type erasure. I know that generic type information is stripped prior to final compilation, replacing type references with Object or boundary types, creating b…
How is compiler inferring type on a generic method?
I have a Storage class: There are two classes where class Child extends Parent: Parent Child Driver class: Because Storage is a generic class, the operations on its method makes sense; I get how case 1 is working. In case 2, with above signature of max in GenericTest, I get the compilation error: The method m…
Nested generic types in static method
I was trying to develop a generic method that could convert a JSON to a generic object that would have another instantiable generic object inside so I could use it as a parser in several places in my application. I had thought of the following solution, but it doesn’t work: Is there any way to be able t…